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	$232.29	13.872%	$264.5133	$264.51	$264.50	$264.50
Purchase #2	$67.83	5.845%	$71.7947	$71.79	$71.80	$71.80
Purchase #3	$100.53	9.292%	$109.8712	$109.87	$109.85	$109.90
Purchase #4	$97.71	3.523%	$101.1523	$101.15	$101.15	$101.20
Purchase #5	$203.79	5.603%	$215.2084	$215.21	$215.20	$215.20
Purchase #6	$106.57	3.509%	$110.3095	$110.31	$110.30	$110.30
Purchase #7	$226.79	5.435%	$239.116	$239.12	$239.10	$239.10
7 purchase totals =	$1,035.51		$1,111.9654	$1,111.96	$1,111.90	$1,112.00