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	$38.38	11.383%	$42.7488	$42.75	$42.75	$42.70
Purchase #2	$196.70	7.427%	$211.3089	$211.31	$211.30	$211.30
Purchase #3	$106.69	4.812%	$111.8239	$111.82	$111.80	$111.80
Purchase #4	$209.76	3.102%	$216.2668	$216.27	$216.25	$216.30
Purchase #5	$38.59	8.574%	$41.8987	$41.90	$41.90	$41.90
Purchase #6	$218.59	8.556%	$237.2926	$237.29	$237.30	$237.30
Purchase #7	$213.27	10.211%	$235.047	$235.05	$235.05	$235.00
7 purchase totals =	$1,021.98		$1,096.3867	$1,096.39	$1,096.35	$1,096.30