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	$43.35	10.585%	$47.9386	$47.94	$47.95	$47.90
Purchase #2	$229.41	6.259%	$243.7688	$243.77	$243.75	$243.80
Purchase #3	$245.77	9.635%	$269.4499	$269.45	$269.45	$269.40
Purchase #4	$92.87	8.459%	$100.7259	$100.73	$100.75	$100.70
Purchase #5	$152.27	5.796%	$161.0956	$161.10	$161.10	$161.10
Purchase #6	$150.83	7.618%	$162.3202	$162.32	$162.30	$162.30
Purchase #7	$104.88	10.276%	$115.6575	$115.66	$115.65	$115.70
7 purchase totals =	$1,019.38		$1,100.9565	$1,100.97	$1,100.95	$1,100.90