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	$34.53	7.300%	$37.0507	$37.05	$37.05	$37.10
Purchase #2	$68.78	4.266%	$71.7142	$71.71	$71.70	$71.70
Purchase #3	$197.29	7.269%	$211.631	$211.63	$211.65	$211.60
Purchase #4	$199.27	12.641%	$224.4597	$224.46	$224.45	$224.50
Purchase #5	$170.94	11.813%	$191.1331	$191.13	$191.15	$191.10
Purchase #6	$147.84	11.685%	$165.1151	$165.12	$165.10	$165.10
Purchase #7	$167.28	4.166%	$174.2489	$174.25	$174.25	$174.20
7 purchase totals =	$985.93		$1,075.3527	$1,075.35	$1,075.35	$1,075.30