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	$172.73	11.133%	$191.96	$191.96	$191.95	$192.00
Purchase #2	$172.66	12.657%	$194.5136	$194.51	$194.50	$194.50
Purchase #3	$88.72	10.404%	$97.9504	$97.95	$97.95	$98.00
Purchase #4	$49.79	4.675%	$52.1177	$52.12	$52.10	$52.10
Purchase #5	$142.77	5.334%	$150.3854	$150.39	$150.40	$150.40
Purchase #6	$215.41	6.629%	$229.6895	$229.69	$229.70	$229.70
Purchase #7	$95.70	7.815%	$103.179	$103.18	$103.20	$103.20
7 purchase totals =	$937.78		$1,019.7956	$1,019.80	$1,019.80	$1,019.90