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	$193.63	8.694%	$210.4642	$210.46	$210.45	$210.50
Purchase #2	$145.62	4.535%	$152.2239	$152.22	$152.20	$152.20
Purchase #3	$238.88	12.807%	$269.4734	$269.47	$269.45	$269.50
Purchase #4	$54.25	6.682%	$57.875	$57.88	$57.90	$57.90
Purchase #5	$214.42	8.798%	$233.2847	$233.28	$233.30	$233.30
Purchase #6	$108.43	4.498%	$113.3072	$113.31	$113.30	$113.30
Purchase #7	$141.30	7.627%	$152.077	$152.08	$152.10	$152.10
7 purchase totals =	$1,096.53		$1,188.7054	$1,188.70	$1,188.70	$1,188.80