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	$72.93	4.508%	$76.2177	$76.22	$76.20	$76.20
Purchase #2	$51.30	3.544%	$53.1181	$53.12	$53.10	$53.10
Purchase #3	$222.91	11.639%	$248.8545	$248.85	$248.85	$248.90
Purchase #4	$46.49	9.331%	$50.828	$50.83	$50.85	$50.80
Purchase #5	$85.69	13.341%	$97.1219	$97.12	$97.10	$97.10
Purchase #6	$83.46	10.402%	$92.1415	$92.14	$92.15	$92.10
Purchase #7	$120.56	5.498%	$127.1884	$127.19	$127.20	$127.20
7 purchase totals =	$683.34		$745.4701	$745.47	$745.45	$745.40