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	$197.65	10.673%	$218.7452	$218.75	$218.75	$218.70
Purchase #2	$210.84	4.841%	$221.0468	$221.05	$221.05	$221.00
Purchase #3	$57.31	4.234%	$59.7365	$59.74	$59.75	$59.70
Purchase #4	$57.61	7.242%	$61.7821	$61.78	$61.80	$61.80
Purchase #5	$58.61	4.495%	$61.2445	$61.24	$61.25	$61.20
Purchase #6	$224.71	13.809%	$255.7402	$255.74	$255.75	$255.70
Purchase #7	$151.33	3.321%	$156.3557	$156.36	$156.35	$156.40
7 purchase totals =	$958.06		$1,034.6510	$1,034.66	$1,034.70	$1,034.50