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	$181.53	8.172%	$196.3646	$196.36	$196.35	$196.40
Purchase #2	$18.40	3.334%	$19.0135	$19.01	$19.00	$19.00
Purchase #3	$18.26	12.776%	$20.5929	$20.59	$20.60	$20.60
Purchase #4	$28.29	6.457%	$30.1167	$30.12	$30.10	$30.10
Purchase #5	$44.32	3.136%	$45.7099	$45.71	$45.70	$45.70
Purchase #6	$12.76	11.465%	$14.2229	$14.22	$14.20	$14.20
Purchase #7	$159.39	6.122%	$169.1479	$169.15	$169.15	$169.10
7 purchase totals =	$462.95		$495.1684	$495.16	$495.10	$495.10