Let's do some math ..  Rounding examples of 7 random hypothetical purchases:
Case	Tag   Price	Sales   Tax %	Raw Total   Incl. Sales Tax	Rounded   to Penny	Rounded   to Nickel	Rounded   to Dime
Purchase #1	$133.93	13.395%	$151.8699	$151.87	$151.85	$151.90
Purchase #2	$199.71	11.276%	$222.2293	$222.23	$222.25	$222.20
Purchase #3	$188.48	4.390%	$196.7543	$196.75	$196.75	$196.80
Purchase #4	$38.28	8.838%	$41.6632	$41.66	$41.65	$41.70
Purchase #5	$146.66	10.741%	$162.4128	$162.41	$162.40	$162.40
Purchase #6	$139.46	10.157%	$153.625	$153.63	$153.65	$153.60
Purchase #7	$240.81	9.153%	$262.8513	$262.85	$262.85	$262.90
7 purchase totals =	$1,087.33		$1,191.4058	$1,191.40	$1,191.40	$1,191.50