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	$193.49	5.722%	$204.5615	$204.56	$204.55	$204.60
Purchase #2	$200.42	5.229%	$210.9	$210.90	$210.90	$210.90
Purchase #3	$116.26	9.590%	$127.4093	$127.41	$127.40	$127.40
Purchase #4	$111.70	10.602%	$123.5424	$123.54	$123.55	$123.50
Purchase #5	$119.88	9.270%	$130.9929	$130.99	$131.00	$131.00
Purchase #6	$215.47	3.568%	$223.158	$223.16	$223.15	$223.20
Purchase #7	$64.73	10.858%	$71.7584	$71.76	$71.75	$71.80
7 purchase totals =	$1,021.95		$1,092.3225	$1,092.32	$1,092.30	$1,092.40