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	$105.26	5.472%	$111.0198	$111.02	$111.00	$111.00
Purchase #2	$238.69	5.632%	$252.133	$252.13	$252.15	$252.10
Purchase #3	$156.63	5.871%	$165.8257	$165.83	$165.85	$165.80
Purchase #4	$65.33	10.470%	$72.1701	$72.17	$72.15	$72.20
Purchase #5	$91.45	3.468%	$94.6215	$94.62	$94.60	$94.60
Purchase #6	$204.64	5.604%	$216.108	$216.11	$216.10	$216.10
Purchase #7	$94.29	4.251%	$98.2983	$98.30	$98.30	$98.30
7 purchase totals =	$956.29		$1,010.1764	$1,010.18	$1,010.15	$1,010.10