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	$61.40	9.375%	$67.1563	$67.16	$67.15	$67.20
Purchase #2	$91.36	7.459%	$98.1745	$98.17	$98.15	$98.20
Purchase #3	$220.94	13.534%	$250.842	$250.84	$250.85	$250.80
Purchase #4	$173.68	12.562%	$195.4977	$195.50	$195.50	$195.50
Purchase #5	$186.87	5.163%	$196.5181	$196.52	$196.50	$196.50
Purchase #6	$108.37	5.501%	$114.3314	$114.33	$114.35	$114.30
Purchase #7	$162.89	13.560%	$184.9779	$184.98	$185.00	$185.00
7 purchase totals =	$1,005.51		$1,107.4979	$1,107.50	$1,107.50	$1,107.50