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	$179.40	11.742%	$200.4651	$200.47	$200.45	$200.50
Purchase #2	$64.30	11.325%	$71.582	$71.58	$71.60	$71.60
Purchase #3	$237.27	4.211%	$247.2614	$247.26	$247.25	$247.30
Purchase #4	$89.98	4.334%	$93.8797	$93.88	$93.90	$93.90
Purchase #5	$86.87	10.643%	$96.1156	$96.12	$96.10	$96.10
Purchase #6	$167.82	12.871%	$189.4201	$189.42	$189.40	$189.40
Purchase #7	$111.38	6.507%	$118.6275	$118.63	$118.65	$118.60
7 purchase totals =	$937.02		$1,017.3514	$1,017.36	$1,017.35	$1,017.40