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	$116.85	9.219%	$127.6224	$127.62	$127.60	$127.60
Purchase #2	$168.33	10.140%	$185.3987	$185.40	$185.40	$185.40
Purchase #3	$205.86	8.400%	$223.1522	$223.15	$223.15	$223.20
Purchase #4	$26.83	3.182%	$27.6837	$27.68	$27.70	$27.70
Purchase #5	$153.86	13.166%	$174.1172	$174.12	$174.10	$174.10
Purchase #6	$98.73	11.180%	$109.768	$109.77	$109.75	$109.80
Purchase #7	$93.56	6.767%	$99.8912	$99.89	$99.90	$99.90
7 purchase totals =	$864.02		$947.6334	$947.63	$947.60	$947.70